Pilz PSS SB HYD, Basic license - Manual (Page 45)

4-15 Modular Block System: Hydraulic Presses
• Valves switched on in start position only
• Operation with or without reaction time monitoring
• An error message is issued if the valve is in the wrong position
• Valve is immediately switched off if an error occurs
• Reset latch when an error is detected
INFORMATION
• If both valve signals are acknowledged via switches, the supply to these
switches must be from test pulses.
• If both valve signals are acknowledged via proximity switches which
cannot be pulsed, the signal lines of the proximity switches must be laid
in different multicore cables within the duct. This will ensure that a short
cannot occur between the two signal lines.
This safety precaution will not be necessary if you use proximity switches
with diverse signals.
• This block is designed for dual valves. You can assume that these will
have a similar switching characteristic. This means that the switch- on
and switch-off times for both valves can be monitored through a single
time parameter for each function.
Please note that when driving structurally separated valves, these will
also show a similar switching characteristic.
WARNING!
The reaction time of the safety valve determines the stopping time of the
press on an emergency stop. The stopping time determines the safety
distance to the tool.
A dangerous situation can arise if parameters for the reaction times are
set values which are greater than the actual reaction time of the valves.
The detailed safety guidelines provided in the SB088 description (see
Chapter 6) must be adhered to at all times.